[12p-D419-1~15] 21.1 合同セッションＫ 「ワイドギャップ酸化物半導体材料・デバイス」

▼ [12p-D419-9] The role of water in the synthesis of AlO_x thin films by a mist chemical vapor deposition

〇(DC)Arifuzzaman Rajib Rajib¹、Abdul Kuddus¹、Karim Enamul¹、Shunji Kurosu²、Tomofumi Ukai²、Yasuhiko Fujii²、Masahide Tokuda²、Tatsuro Hanajiri²、Ryo Ishikawa¹、Keiji Ueno¹、Hajime Shirai¹ (1.Saitama Univ.、2.Toyo Univ.)

キーワード：mist-CVD, Alumina, Water addition

The role of water as an additive during the synthesis of aluminum oxide (AlO_x) thin films by mist chemical vapor deposition (mist CVD) was investigated. This study was based on deposition using aluminum acetylacetonate (Al(acac)₃) and methanol (MeOH), while also exposing some films to water or methanol mists after fabrication. Analysis by AFM and FTIR spectroscopy established that the AlO_x films fabricated from Al(acac)₃ using methanol as the sole exhibited a distorted Al(OH) network, including a high concentration of OH groups. The addition of water to the Al(acac)₃/MeOH precursor decreased the film deposition rate and also lead to marked reductions in both the surface roughness and -OH concentration. Exposing the Al(OH) films to water mist after synthesis resulted in etching together with the removal of -OH groups and decreases in surface roughness. Exposure to water induced no significant changes in the surface chemistry or morphology of AlO_x thin films deposited at a MeOH:water volume ratio of 7:3. However, FTIR spectra demonstrated that exposing these AlO_x films to a MeOH mist promoted the formation of Al(OH) bonds. Figure 1 shows the schematic of the growth surface for the MeOH:water ratios of 10:0 and 7:3. The results of this work indicate that the incorporation of -OH groups into the AlO_x network generates both network distortion and inhomogeneity. It is also evident that water present during film growth removes -OH groups during the growth, resulting in the formation of a dense, uniform AlO_x network. The effect of the substrate bias on the AlO_x film properties will be also presented.